Messages in this thread | | | Date | Wed, 19 Aug 2009 10:41:51 +0900 | Subject | abnormal OOM killer message | From | 우충기 <> |
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Hi all~ I have got a log message with OOM below. I don't know why this phenomenon was happened. When direct reclaim routine(try_to_free_pages) in __alloc_pages which allocates kernel memory was failed, one last chance is given to allocate memory before OOM routine is executed. And that time, allocator uses ALLOC_WMARK_HIGH to limit watermark. Then, zone_watermark_ok function test this value with current memory state and decide 'can allocate' or 'cannot allocate'.
Here is some kernel source code in __alloc_pages function to understand easily. Kernel version is 2.6.18 for arm11. Memory size is 32Mbyte. And I use compcache(0.5.2). ------------------------------------------------------------------------------------------------------------------------------------------------------------- ... did_some_progress = try_to_free_pages(zonelist->zones, gfp_mask); <== direct page reclaim
p->reclaim_state = NULL; p->flags &= ~PF_MEMALLOC;
cond_resched();
if (likely(did_some_progress)) { page = get_page_from_freelist(gfp_mask, order, zonelist, alloc_flags); if (page) goto got_pg; } else if ((gfp_mask & __GFP_FS) && !(gfp_mask & __GFP_NORETRY)) { <== when fail to reclaim /* * Go through the zonelist yet one more time, keep * very high watermark here, this is only to catch * a parallel oom killing, we must fail if we're still * under heavy pressure. */ page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, order, <== this is last chance zonelist, ALLOC_WMARK_HIGH|ALLOC_CPUSET); <== uses ALLOC_WMARK_HIGH if (page) goto got_pg;
out_of_memory(zonelist, gfp_mask, order); goto restart; } ... -------------------------------------------------------------------------------------------------------------------------------------------------------------
In my case, you can see free pages(6804KB) is much more higher than high watermark value(1084KB) in OOM message. And order of allocating is also zero.(order=0) In buddy system, the number of 4kbyte page is 867. So, I think OOM can't be happend.
How do you think about this? Is this side effect of compcache? Please explain me. Thanks.
This is OOM message. ------------------------------------------------------------------------------------------------------------------------------------------------------------- oom-killer: gfp_mask=0x201d2, order=0 (==> __GFP_HIGHMEM, __GFP_WAIT, __GFP_IO, __GFP_FS, __GFP_COLD) [<c00246c0>] (dump_stack+0x0/0x14) from [<c006ba68>] (out_of_memory+0x38/0x1d0) [<c006ba30>] (out_of_memory+0x0/0x1d0) from [<c006d4cc>] (__alloc_pages+0x244/0x2c4) [<c006d288>] (__alloc_pages+0x0/0x2c4) from [<c006f054>] (__do_page_cache_readahead+0x12c/0x2d4) [<c006ef28>] (__do_page_cache_readahead+0x0/0x2d4) from [<c006f594>] (do_page_cache_readahead+0x60/0x64) [<c006f534>] (do_page_cache_readahead+0x0/0x64) from [<c006ac24>] (filemap_nopage+0x1b4/0x438) r7 = C0D8C320 r6 = C1422000 r5 = 00000001 r4 = 00000000 [<c006aa70>] (filemap_nopage+0x0/0x438) from [<c0075684>] (__handle_mm_fault+0x398/0xb84) [<c00752ec>] (__handle_mm_fault+0x0/0xb84) from [<c0027614>] (do_page_fault+0xe8/0x224) [<c002752c>] (do_page_fault+0x0/0x224) from [<c0027900>] (do_DataAbort+0x3c/0xa0) [<c00278c4>] (do_DataAbort+0x0/0xa0) from [<c001fde0>] (ret_from_exception+0x0/0x10) r8 = BE9894B8 r7 = 00000078 r6 = 00000130 r5 = 00000000 r4 = FFFFFFFF Mem-info: DMA per-cpu: cpu 0 hot: high 6, batch 1 used:0 cpu 0 cold: high 2, batch 1 used:1 DMA32 per-cpu: empty Normal per-cpu: empty HighMem per-cpu: empty Free pages: 6804kB (0kB HighMem) Active:101 inactive:1527 dirty:0 writeback:0 unstable:0 free:1701 slab:936 mapped:972 pagetables:379 DMA free:6804kB min:724kB low:904kB high:1084kB active:404kB inactive:6108kB present:32768kB pages_scanned:0 all_unreclaimable? no lowmem_reserve[]: 0 0 0 0 DMA32 free:0kB min:0kB low:0kB high:0kB active:0kB inactive:0kB present:0kB pages_scanned:0 all_unreclaimable? no lowmem_reserve[]: 0 0 0 0 Normal free:0kB min:0kB low:0kB high:0kB active:0kB inactive:0kB present:0kB pages_scanned:0 all_unreclaimable? no lowmem_reserve[]: 0 0 0 0 HighMem free:0kB min:128kB low:128kB high:128kB active:0kB inactive:0kB present:0kB pages_scanned:0 all_unreclaimable? no lowmem_reserve[]: 0 0 0 0 DMA: 867*4kB 273*8kB 36*16kB 2*32kB 0*64kB 0*128kB 0*256kB 1*512kB 0*1024kB 0*2048kB 0*4096kB = 6804kB DMA32: empty Normal: empty HighMem: empty Swap cache: add 4597, delete 4488, find 159/299, race 0+0 Free swap = 67480kB Total swap = 81916kB Free swap: 67480kB 8192 pages of RAM 1960 free pages 978 reserved pages 936 slab pages 1201 pages shared 109 pages swap cached Out of Memory: Kill process 47 (rc.local) score 849737 and children. Out of memory: Killed process 49 (CTaskManager). Killed SW image is stopped.. script in BOOT is stopped... Starting pid 348, console /dev/ttyS1: '/bin/sh' -sh: id: not found # -------------------------------------------------------------------------------------------------------------------------------------------------------------
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